All these things are true of Drive, though. The only real reason I haven't switched over is, like you, all my stuff is already in Dropbox, and they're pretty much the same thing, so I wouldn't gain that much by switching (I actually use Drive too, but only for its original form, Docs). The new price is a big discount, but we'll have to see if Dropbox moves to match it in some way (they have less room to optimize there, but it's certainly feasible...amazon has been cutting their rates too).
If I was new to the market, though, none of that reasoning really applies.